A STUDY  OF  METHODS  FOR  SEPARATION  AND  IDENTIFI- 
CATION OF  COMPLEX  AROMATIC  HYDROCARBONS 
OBTAINED  IN  THE  CATALYTIC  DECOMPOSITION 
OF  XYLENES 

BY 

JOHN  DANIEL  MALECKI 


THESIS 


FOR  THE 

DEGREE  OF  BACHELOR  OF  SCIENCE 

IN 

CHEMICAL  ENGINEERING 


COLLEGE  OF  LIBERAL  ARTS  AND  SCIENCES 
UNIVERSITY  OF  ILLINOIS 


1922 


UNIVERSITY  OF  ILLINOIS 


January.. .2.6., 19122. 


THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 


John. ..Daniel.  Male.cJci 


ENTITLED. .. A.. S.tudy...oi... Methods.. .ior .. Separation.. . and. ..Identifi,ca.tiQn.... 

of  Complex  Aromatic  Hydrocarbons  Obtained  in  the  Catalytic 
Decpmpp  s i t i on  of  .Xylene  s 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 

DEGREE  OF Bachelor-of  •Science 

in 

.Chemical.. .Engineering 


Approved 


HEAD  OF  DEPARTMENT  OF 


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Acknowledgement. 


T . 


This  investigation  was  carried  on  in  the  chemical 
laboratory  of  the  University  of  Illinois, during  the 
collegiate  years  1920-1921.  The  problem  was  one  arising 
directly  from  an  extended  investigation  carried  on  by 
Dr.  M. J. Bradley , and  was  carried  out  under  the  general 
supervision  of  Professor  S.W.Parr. 

I am  grateful  to  Professor  Parr  for  his  kindness 
and  the  inspiration  he  has  given  me  in  the  course  of  the 
v/ork,and  in  no  less  degree  to  Dr. Bradley  to  whom  I am 
indebted  for  the  materials  used, as  well  as  a large  part 
of  the  apparatus.  His  suggestions  and  assistance  have 
likewise  been  invaluable  to  me  in  the  investigation. 


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2. 


Table  of  Contents. 

Page 

I Introduction 

1 .  Preliminary  4 

2.  General  Considerations  4 

3.  Previous  Investigations  6 

4. Outline  of  Present  Investigation  11 

II  Experimental  Work 

1.  Elementary  Analysis  of  Xylene  and  Tar  15 

2.  Fractional  Distillation  16 

3.  Approximate  Determination  of  Physical  Constant si 7 

4.  General  Appearance  of  Compounds  19 

5.  Determination  of  Behavior  Towards  Solvents  19 

Separation  of  Liquids  From  Solids  23 

7.  Isolation  of  Compounds  Possible  by  Solubility 

Behavior  24 

8.  Steam  Distillation  of  Liquids  and  Solids  26 

9.  Special  Methods  of  Purification  28 

10.  Accurate  Determination  of  Physical  Constants  29 

11.  Application  of  Class  Reactions  29 

12.  Specific  Tests  and  Choice  of  Derivative  30 

13.  Hydrocarbons  in  Straight  Xylene  Runs  30 

14.  Hydrocarbons  in  Xylene- ethylene  Runs  36 

15*  Manipulation  of  Napthalene  Run  Products  38 

16.  Hydrocarbons  in  Napthalene  Runs  39 

17.  Approximate  Yields  in  Each  Case  40 

18.  Methods  of  Separation  Best  Adapted  41 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive;org/details/studyofmethodsfoOOmale 


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19.  Some  Special  Aspects  of  the  problem 
III  Summary 
IV  Bibliography 
V Vita 


Pa/3;e 

42 

44 

47 

49 


4. 


A STUDY  OF  METHODS  FOR  SEPARATION  AIH)  IDENTIFICATION 
OF  COMPLEX  AROMTIC  HYDROCARBONS  OBTAINED 
IN  THE  CATALYTIC  DECOMPOSITION 
OF  XYLENES. 


I.  Introduction. 

1 . Prelimlnai^y . Aromatic  hydrocarbons  underp;o  complex  re- 
arranp;ements, decompositions, and  building  up  when  subjected  to 
certain  conditions  of  heat , pressure  and  catalytic  agents.  This 
property  suggests  the  possibility  of  subjecting  the  less  val- 
uable fractions  obtained  from  coal  tar  to  carefully  governed 
conditions  and  producing  substances  of  greater  value.  The  work 
here  undertaken  has  been  an  attempt  at  separation  and  ident- 
ification of  the  constituents  of  a mixture  produced  by  Just 
such  a process. 

2.  G-eneral  considerations.  With  the  view  that  a knowledge  of  the 
possible  compounds  which  might  be  included  in  the  substances 
investigated, would  be  of  considerable  value  in  shaping  the 
general  procedure  of  the  investigation,a  brief  consideration 
of  the  various  factors  involved  in  the  manner  of  obtaining  the 
substances  is  important.  In  the  actual  process  of  decomposition 
the  well  recognized  and  most  easily  controlled  variables  are 
those  of  temperature, pressure, and  catalysis.  The  generally 
accepted  order  of  decomposition  of  aromatic  hydrocarbons  under 
heat  is  as  follows;  Higher  benzene  homologues  -slower  benzene 


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homoloQ;ues  benzene  diphenyl  napthalene  -t  anthracene 
carbon  and  gas. 

Under  actual  conditions  this  does  not  occur  with  the  ease 
and  smoothness  indicated  above, but, on  the  contrary,  the  reactions 
are  infinitely  more  complicated  than  that , although  proceeding 
in  the  general  direction  shown.  Each  decomposition  product  is 
in  contact  with  the  original"  substance  or  substances, and  with 
other  larger  molecules  which  have  already  been  formed; the  whole 
being  at  a high  temperature  and  probably  in  an  extremely  unstable 
condition.  These  vapors , may , therefore  be  considered  practically 
as  atomic  hydrogen  and  carbon  in  indefinite  proportions  waiting 
upon  some  factor  to  create  a condition  in  which  they  will 
coalesce  into  a definite, stable  molecule.  The  high  temperature 
involved, the  kinetic  theory  of  gases, and  the  composition  of  the 
gaseous  residues  all  point  to  the  fact  that  this  condition, 
while  not  actually  existing  is  approximated  very  closely.  If  the 
problemlcal  3CJH,  =GH2,and-CH^  residues  can  exist  in  the  free 
state  at  all  they  would  certainly  be  present  in  a furnace  during 
a run, and  although  actual  proof  is  lacking, it  is  conceded  that 
they  are  present  under  such  conditions, if  only  momentarily.  The 
collision  of  two  gaseous  molecules  of  xylene, for  example, which 
results  in  the  detaching  of  a-CH^  group  occurs  continually , and 
there  must  be  a certain  amount  of  -CH-^  continually  present,  even 
though  it  reacts  immediately  with  some  other  substance.  Conc- 
entration of  various  residues  in  the  vapor, are  seen  to  have 
considerable  influence  on  the  products  formed. 

It  can  be  seen  from  the  foregoing  discussion, that  the 
possibilities  of  the  combinations  present  are  practically  un- 


■’  ii 


6. 

limited, and  actually ,p;reat  numbers  of  compounds  are  formed, thoup;h 
comparatively  few  in  any  quantity  due  to  the  equilibria  rapidly 
reached  under  a given  set  of  conditions. 

Again, unfortunately , hydrocarbons  of  such  a nature  are  diff- 
icult of  separation  due  to  their  closely  related  nature.  Their 
action  toward  solvents  and  reagents  do  not  differ  greatly, and 
inseparable  mixtures  are  the  r*'jile,not  the  exception.  In  the  making 
of  derivatives  the  slightest  contamination  of  the  substance  under 
investigation  will  generally  reappear  in  like  proportion  in  the 
derivative, or  will  make  the  reaction  fail  altogether. 

In  this  work  we  have  endeavored  to  effect  the  separations  by 
means  of  solvents  as  far  as  possible, and  after  obtaining  a 
quantity  of  the  pure  substance, to  identify  it, and  determining, by 
comparative  data, the  most  practical  method  of  purification.  No 
quantitative  results  were  attempted  as  the  majority  of  the  runs  . 
were  combined  with  each  other  to  form  one  sample.  A few  compounds 
were  very  much  in  evidence  in  spite  of  this. 

Scope  of  Previous  Investigations.  Extensive  study  has  been  made 
of  the  effect  of  heat  on  aliphatic  hydrocarbons  and'  in  a lesser 
degree  on  aromatic  hydrocarbons.  Aromatic  substances  are  more 
stable  under  these  conditions, and  the  products  are  less  easily 
controlled  besides  being  of  less  value  than  those  obtained  in 
petroleum  cracking.  It  is  natural , therefore,  that  the  former  has 
been  the  most  thoroughly  investigated, although  some  very  compre- 
hensive studies  have  been  made  at  various  times  on  the  aromatics. 
Identification  data  seems, rather  peculiarly , to  be  lacking  in  the 
literature  on  the  subject; the  endproducts  being  in  some  cases 
just  mentioned  by  name  without  stating  the  evidence  which  proved 


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the  Identity  of  the  compound  in  question.  Some  investip;ator3  offer 
as  proof  a melting  point  or  boiling  point, while  others  give  some 
methods  of  isolation  with  complete  identification  data, but  these 
are  rare. 

The  early  investigators  lacked  some  of  the  p.dvantages  offered 
by  the  systematic  methods  of  identification  of  organic  compounds 
now  in  use, although  these  methods  are  still  far  from  satisfactory 
in  dealing  with  this  type  of  mixtures.  Former  methods  of  ident- 
ification were  probably  as  complete  as  circumstances  would  permit, 
but  many  erroneous  assumptions  were  made  which  were  later  correct- 
ed by  succeeding  investigators.  As  an  example,Berthelot, the 
pioneer  investigator  in  this  field, claimed  to  have  obtained 
chrysene  in  his  re searches, and  it  was  later  proven  by  Schmidt  and 
Shultz  that  this  was  not  so,a,nd  that  the  compound  referred  to  by 
Berthelot  which  melted  af'about  200°"  was  a mixture  of  the  methyl 
anthracenes, and  not  chrysene  which  has  a melting  point  of  250°. 

Zanetti  and  Egloff  '^distilled  the  products  they  obtained  from 
the  thermal  decomposition  of  benzene  with  a Glinsky  column, and 
merely  stated  that  the  fraction  boiling  from  250-275°  contained 
diphenyl, and  that  the  fraction  distilling  from  200-250®  might  be 
considered  as  napthalene.  The  higher  boiling  fractions  they 
extracted  with  alcohol  and  obtained  products  melting  at  86®  and 
196®  which  they  called  the  m & p diphenyl  benzenes  and  triphenylene 
respectively. 

Clark^ Ogives  methods  of  seperation  of  anthracene, carbazol  and 
phenanthrene  in  detail.  Although  nitrogen  compounds  are  absent  in 
the  materials  investigated  in  this  Virork,both  anthracene  and  phen- 
anthrene may  be  present  so  the  article  was  studied  in  detail.  In 


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8. 


their  process  the  solids  are  allowed  to  settle  out, filtered  from 

the  accompanying  liquids  as  far  as  possible, and  then  sub.iected  to 

solvent  methods.  Coal  tar  naptha  was  used  to  remove  phenantlirene 

and  coal  tar  bases  until  a limiting  purity  is  obtained, then  acetone 
are 

and  pyridene  used  to  isolate  the  anthracene; these  solvents 
dissolving  out  the  two  principal  impurities  left ,ph'enanthrene  and 
carbazol , finally  the  anthracene  was  heated  until  it  passed  into 
solution, filtered  and  crystallized.  The  purity  of  the  product  was 
claimed  to  be  sufficiently  high  for  commercial  purposes.  The 
phenanthrene  was  recrystallized  from  gasoline  and  then  from  alcohol 
with  bone  black, and  obtained  as  a pure  white  solid  M.P.IDO®. 

Rittman, Byron  and  Egloss^^  arrived  at  three  fundamental  con- 
clusions in  their  investigations  of  the  thermal  reactions  of 
hydrocarbons  in  the  vapor  phase;  a)  The  course  of  the  reaction  is, 
in  general  in  the  direction  of  decrease  in  the  size  of  the  molecule 
when  the  degree  of  saturation  is  unchanged, b)  Reaction  may  occur 
in  the  direction  of  dehydrogenation  with  either  an  increase  or 
decrease  in  the  size  of  the  molecule, c)  Reverse  reactions  are 
negligible.  They  distilled  their  products  fractionally , and 
arbitrarily  named  each  fraction  according  to  its  corresponding 
coal  tar  fraction, the  solids  being  assumed  to  be  napthalene  and 
anthracene. 

An  investigation  on  the  formation  of  anthracene  from  benzene 
and  ethylene  gives  a method  for  the  quantitative  determination  of 
anthracene  by  oxidation  of  the  entire  anthracene  fraction  to  anthra- 
quinone,and  subsequently  purifying  the  product.  This  is  not  necess- 
arily an  index  of  the  anthracene  present  as  there  are  several 
closely  related  hydrocarbons  besides  anthracene  Virhich  yield  anthra- 


i 


9. 


quinone  on  oxidation. 

A very  complete  Identification  of  compounds  produced  under 
conditions  similar  to  those  utilized  in  makinj^  the  substances 
investigated  in  this  problem  is  found  in  the  report  of  the  work 
of  Cook  and  Chambers?^  They  hydrolized  their  product  and  steam 
distilled, obtaining  in  the  first  fraction  benzene,  toluene, and 
xylene.  The  heavier  products, which  steam  distilled  less  readily, 
were  fouind  to  consist  of  an  oil  boiling  between  280-290°  which 
they  proved  to  be  unsymmetrical  diphenyl- ethane  having  a 
boiling  point  of  286^  by  oxidation  to  benzophenone  and  subsequent 
formation  of  the  oxime  M.P.140°.  Still  higher  boiling  compounds 
from  360°  up, they  recrystallized  from  alcohol  and  found  to  have 
a melting  point  of  181*^.  This  they  oxidized  to  anthraquinone  and 
assumed  to  be  9-10  dimethyl-anthracene-hydride.  A fraction 
boiling  from  290-300^  was  oxidized  in  an  acetic  chromic  acid 
solution  to  its  oxida-tion  product  and  subsequently  converted  to 
the  oxime  which  melted  at  163°  indicating  the  presence  of  unsym- 
p-ditolyl-ethane  B. P. 294-295°. 

They  also  obtained  some  brown  needles  which  they  were  able  to 
oxidize  to  anthraquinone  and  assumed  to  be  2-7  dimethyl-anthracene. 

D. T. Jones'^^^  gives  no  identifications  on  his  products, but 
he  states  that  he  removed  the  methyl  napthalenes  from  the  oils  by 
treatment  with  picric  acid.  He  gives  an  interesting  discussion  on 
the  formation  of  napthalene  from  phenyl-butylene  and  on  the 
formation  of  phenanthrene  from  o-ditolyl. 

Bone  and  Coward‘S  give  no  identifications  in  their  article  on 
decomposition  of  hydro  carbons,  and  G-.W.McKee^  ^ uses  a polarizing 
microscope  in  his  work  on  the  products  of  the  decomposition  of 


• • s 


10. 


benzene.  C.  Smith  and  W-Lewcock^"^  investigated  only  the  presence 
of  diphenyl  in  their  problem. 

Haber^  in  his  researches  on  pyrogenetic  reactions  of  aliph- 
atic hydrocarbons , does  not  mention  that  he  obtained  any  of  the 
higher  degree  aromatic  compounds.  Libermann  and  Berg^T  in  their 
researches  in  I878  mention  that  they  obtained  anthracene, a yellow, 
butterlike  mass  which  they  oxidized  to  anthraquinone  with  chromic 
acid  in  acetic  acid  solution, and  then  converted  the  anthraquinone 
into  alazarin.  They  obtained  napthalene,but  did  not  mention 
further  identifications, although  they  claimed  chrysene  to  be 
present  with  other  aromatic  compounds.  Ostromisslenski  and 
Burshanadse^ ^ evidently  carried  out  their  hydrocarbon  decomp- 
osition with  a view  of  obtaining  hydrogen  for  balloons, and  no 
compounds  were  mentioned. 

Smith  and  Shultz^'^  gave  a few  valuable  hints  in  their  article 
relative  to  their  researches.  They  carried  on  benzene  decompositior 
by  methods  similar  to  those  employed  by  Berthelot,  and  they  first 
distilled  fractionally  their  high  boiling  compounds.  The  fraction 
boiling  under  100*^  they  considered  as  benzene, and  they  noted  that 
the  thermometer  ran  right  up  to  the  point  where  diphenyl  began 
distilling.  They  collected  the  diphenyl  and  identified  it.  Cuts 
were  then  made  at  250^,300®, and  finally  at  360%fter  ivhich  they 
examined  the  fractions  separately.  That  coming  over  above  300*^ 
was  a bright  yellow  solid, and  the  residue  in  the  flask  was  a 
brownish  powder.  They  identified  their  compounds  by  physical  con- 
stants , solubilities,  reactions  with  picric  acid, likewise  placing 
great  reliance  on  the  crystalline  structure  of  the  compounds 
under  consideration. 


11. 


COI-CPOUND  CRYST.STR.  M.P.  B.P.  ALC.SOL.  PI  CRATE 
diphenyl  benzene  leaflets  205°  383°  difficultly  none 
^ diphenyl  " 70.5°  254°  soluble  ^ " 

isodiphenylbenzyl  needles  85°  363°  " " 

triphenylene  " 196*^  36o°up  slightly  yes 

benzerythrene  plates  307-8°  High  insol.  none 

Benzerythrene  is  in  the  residue  after  extracting  with  alcohol. 
Trlphenyle^e  was  described  as  a yellow  compound, and  v/as  mentioned 
to  be  identical  with  the  compound  that  Berthelot  designated  as 
chrysene.  The  oils  proved  unmanagj,ble,but  they  identified  a 
compound  with  the  formula(C5H5GH2 in  the  high  boiling 
oils. 

» 

4. Outline  of  Present  Investl-g^atlon.  The  fact  that  in  the  distill- 
ation of  low  temperature  tars, there  is  a relatively  large  fraction 
' which  is  of  little  or  no  commercial  import^ance.  This  fraction 
consists  principally  of  the  three  isomeric  xylenes, which  have  too 
high  'h  boiling  point  for  a motor  fuel^and  are  of  no  importance 
otherwise.  If  this  fraction  could  be  converted  into  other  more 
useful  substances  by  thermal  decomposition, use  could  be  made  of 
large  quantities  of  this  oil  which  now  has  no  practical  applic- 
ation. 

Following  this  line  of*  reasoning, the  vapors  of  the  mixed 
xylenes  were  passed  through  a furnace  containing  various  catalysts, 
and  under  various  conditions  of  temperature  and  pressure, which 
are  exhaustively  described  in  the  thesis  of  Dr. M.J. Bradley^ 

A wide  variety  of  substances  were  produced, but  we  are  concerned 
only  with  the  substa.nces  formed  which  have  a higher  boiling  point 


I 


i 

\ 

t • 

} 


\ 


12. 


than  the  origional  xylenes, or  roughly , above  150°, the  other 
products  condensible  and  noncondensible  being  identified  in  the 
course  of  Dr. Bradleys  work. 

In  this  Investigation  the  products  obtained  were  first  fract- 
ionally distilled; cuts  being  made  at  about  every  twenty  degrees. 
These  fractions  were  then  extracted  with  solvent Sj or  otherwise 
treated  by  methods  adapted  from  the  scant  literature  on  the  subject 
and  by  other  methods  which  in  the  course  of  the  invostiga,tion 
seemed  to  give  promise  of  good  results. 

In  the  distillation  of  the  hydrocarbons  they  came  over, in 
general, in  the  oiTder  of  increasing  specific  gravity;  the  very 
light  oils  distilling  first, the  heavier  oils  coming  next  with 
increasing  amounts  of  solids  in  suspension, and  finally  the  very 
heavy , syrupy  oils  and  large  amounts  of  solids  are  driven  over. 

These  fractions  grade  gradually  one  into  another, and  no  separation 
is  possible  by  fractionation , except  in  a general  way. 

Unlike  petroleum  distillation  products , these  substances 
cannot  be  used  as  distilled, but  they  must  first  be  subjected  to 
purification, as  it  is  the  pure  compoimds  which  are  important  in 
the  case  of  aromatic  hydrocarbons.  Aliphatic  hydrocarbons  do  not 
differ  markedly  from  those  in  their  immediate  neighborhood, and 
for  all  practical  purposes  fractionation  effects  ample  separation. 
It  ca,n  easily  bet  seen  that  the  difficulties  be  equally  great 
in  separating  a-methyl  napthalene  from  its  accompanying  oils  as 
separating  pure  hexane  from  gasoline. 

Many  of  these  aromatic  hydrocarbons  are  used  pure  in  the 
manufacture  of  various  types  of  dyes, so  a commercial  means  of 
separating  them  from  these  synthetic  mixtures  obtained  from 


I 

< 


13. 


coal  tar  fractions  v^rould  be  of  considerable  value  to  the  dye 
industry. 

Separation  methods  which  are  worthy  of  trial  are  steam  dist- 
illation, centrifuging,  fractionation,  separation  by  specific 
gravity  difference, and  separation  by  behavior  towards  reagents 
and  solvents. 

A sample  of  the  total  run  was  examined  for  the  elements, and 
another  portion  was  subjected  to  the  class  reactions  for  organic 
compounds  . Steam  distillation  was  employed  continually , as  was 
distillation  under  diminished  pressure.  Identification  of  a 
compound  after  isolation  was  effected  by  determining  its  physical 
constants  and  appearance, looking  up  in  the  literature  the 
compound  corresponding  to  the  one  in  question  most  closely, and 
finally  making  a derivative  of  the  compound  and  obtaining  its 
physical  constants  and  comparing  them  to  the  literature  values. 

Melting  points  are  the  most  common  physical  constants 
employed , although  boiling  points  and  specific  gravities  are  used 
to  some  extent. 

Only  rough  approximations  were  made  as  to  quantitative  results, 

/ 

as  in  many  cases  the  runs  were  combined  in  groups  to  form  a single 
sample, thus  making  quantitative  results  of  little  value. 

After  the  preliminary  tests  which  were  applied  to  the  crude 
tar, the  bulk  of  the  tar  was  distilled  fractionally  in  an  elect- 
rically heated  distilling  flask, which  is  fully  explained  in 

detail , together  with  the  manner  of  making  same, in  the  thesis 

20 

prepared  by  Charleton  . This  general  separation  preceded  the 
special  methods  which  were  then  applied  separately  to  the  liquids 
and  solids  as  described  fully  later.  The  last  traces  of  xylene 


f 


) 


I 

I 

I 


V 

» 

r 

i 

i: 

t; 


I 


f 


14. 


were  removed  by  steam  distillation  and  subsequent  refractionation. 
The  solids  were  treated  with  solvents  except  in  a few  exceptional 
cases. 

The  napthalene  runs  were  steam  distilled; the  napthalene 
thus  recovered  was  fractionated, and  the  products  not  volatile  v/ith 
steam  were  examined  in  detail.  The  data  on  these  runs  will  be 
grouped  together  later. 

No  combustions  were  considered  necessary, as  all  of  the 
compounds  are  known  and  can  be  found  in  the  literature, so  the 
obtaining  of  the  two  physical  constants  and  the  making  of  a 
derivative  was  considered  sufficient  identification. 


\ 


15. 


II  Experimental  Work. 

1 . Elementary  analysis  of  xylene  and  tars  for  elements.  A pre- 
liminary ignition  of  the  xylene  and  the  resultant  crude  tar  on 
platinum  foil  gave  no  Inorganic  residue  in  either  case, although 
there  was  a heavy  deposit  of  carbon  from  the  tar; so  it  was 
assumed  that  inorganic  matter  was  entirely  absent. 

The  test  for  the  organic  elements  was  made  in  the  usual 
manner.  A piece  of  clean  metallic  sodium  was  placed  in  a two 
inch  test  tube, heated, and  several  drops  of  the  substance  in- 
vestigated, dropped  in, care  being  taken  to  have  it  react  with 
the  sodium  vapors.  The  tube  was  then  ignited  to  a red  heat  and 

plunged  into  ten  cubic  centimeters  of  cold  distilled  water. 

/ 

This  is  then  boiled, filtered, the  solution  obtained  being  ready 
for  the  tests  for  sulphur, nitrogen, and  the  halogens. 

In  testing  for  sulphur, a few  cubic  centimeters  of  the  solu- 
tion was  acidified  slightly  with  acetic  acid, and  a few  drops 
of  lead  acetate  were  added.  No  sulphur  was  found  in  the  xylene, 
but  in  the  tar  a very  small  amount  was  detected.  A second 
trial  confirmed  this.  It  is  hard  to  account  for  the  appearance 
of  sulphur, but  in  all  probability  it  was  a.bsorbed  from  the 
pumice  stone  and  the  other  catalysts  used. 

In  testing  for  nitrogen  a few  cubic  centimeters  of  the 
stock  solution  are  boiled  with  five  drops  of  FeSO^and  one  drop 
of  FeCl^  for  two  minutes.  It  is  then  cooled, and  just  acidified 
v/ith  dilute  HCl.  The  xylene  gave  a clear  yellow  solution  on 
acidification, but  the  tar  sample  gave' a light  green  solution 
which  on  filtering  through  a hard  filter  left  a slight  blue 


16. 

stain  on  the  paper, Indicatinp;  a trace  of  nitrogen.  This  also  was 
confirmed. 

For  halogens  the  solution  is  acidified  with  nitric  acid, boil- 
ed a few  minutes , cooled , and  a few  drops  of  silver  nitrate  added. 
The  solution  remained  clear  in  both  cases  indicating  a total 
absence  of  halogens. 

2.  Fractional  distillation.  During  fractionation , cuts  were  made 
at  much  more  frequent  intervals  than  would  be  maide  on  a commer- 
cial scale  for  better  observation  of  the  products  obtained.  Many 
of  these  fractions  were  combined  again  later, when  it  was  found 
that  they  v;ere  of  the  same  composition. 

The  distillations  were  carried  out  either  in  an  electrically 
heated  distilling  flask  or  in  a flask  immersed  in  a sand  bath, 
which  latter  method, though  being  cruder, y/as  fully  as  efficient 
and  had  all  of  the  advantages  of  the  electrical  outfit.  An  air 
condenser  was  used  throughout , as  the  substances  were  all  so  heavy 
that  they  condensed  almost  immediately  in  the  side  tube  of  the 
distilling  flask.  As  far  as  could  be  observed  there  was  no 
decomposition  due  to  cracking  until  the  temperature  was  well 
over  300°, after  which  there  was  some  indication  that  cracking 
occurred. 

In  the  mixed  runs  the  first  fraction  was  collected  between 
the  temperatures  150° and  210°.  This  was  a rather  large  fraction, 
but  was  found  later  to  consist  largely  of  xylene  and  a very 
small  quantity  of  a higher  boiling  oil.  The  next  fraction  was 
taken  from  211°  to  240^  so  that  any  napthalene  which  might  be 
present  would  be  included, after  that  regular  cuts  were  made  at 
260° , 280° , 300° , 330° , 360° , and  until  nothing  further  came  over. 


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17. 


The  two  ethylene  runs  were  fractioned  still  more  carefully; as 
there  was  a greater  volume  of  them, and  a greater  variety  of 
compounds  were  expected^ The  distillation  was  carried  out  in  the 
electric  stills, cuts  being  made  at  150°, 175°, 200°, 225°, 240°, 

255°, 300°, 550°, 400°, 500°, and  until  nothing  further  came  over. 

The  residual  coke  was  saved  for  future  reference  in  all  cases. 

3.  Approximate  determination  of  physical  constants.  The  boiling 
points  were, of  course, noted  in  the  course  of  the  distillation. 
Melting  points  on  the  solids  produced , taken  after  there  solids 
were  pressed  free  of  the  oil, proved  to  be  of  little  value  even 
approximately , for  the  oil  which  remained  in  them  lowered  the 
true  melting  point  from  twenty  to  sixty  degrees  as  was  later 
found  out. 

Specific  gravities  of  the  oils  in  the  ethylene  series, 
which  were  considered  representative  of  all  of  the  substances 
obtained, were  next  acertained  by  means  of  an  accurately  calibr- 
ated pyknoraeter(l  c.c.).  These  determinations  were  carried  out 
under  a constant  temperature  of  15.5°C,and  the  weight  of  the  tube 
was  checked  three  times  during  the  course  of  the  determination. 
The  specific  gravities  found  v/ere  as  follows. 


Origional  xylene  0.8664 

Tar  (as  obtained) I.O808 

Fraction  145-175° O.89II 

175-200°  Fraction  0.9057 

200-225°  ” 0.9605 

225-240°  " 0.9888 

240-255°  ” 1.0087 

255-300°  " 1.0282 


18. 


300-350°  Fraction  I.0625 

I 

350-400°  " 1.1082 


Some  of  these  liquids  undoubtedly  had  solids  in  solution, 
thus  introducing  an  error  in  the  determinations, but  this  error 
is  slight, as  the  solids  involved  have  practically  the  same 

specific  gravity, when  in  the  liquid  state, as  the  liquids  with 
which  they  distill. 

The  boiling  range  of  the  original  xylene  was  the  next  thing 
taken  into  consideration.  The  specifications  were  that  it  should 
boil  between  140°  and  1 43°, actually  the  range  was  as  follows.  A 
common  distilling  flask  and  condenser  were  used, the  bottom  of  the 
flask  being  well  covered  with  glass  beads  to  insure  smooth  boiling, 
one  hundred  cubic  centimeters  of  xylene  were  used. 


1 st 

drop 

--  125° 

1 St 

10 

c.  

2nd 

10 

c . c. 

--  138-139° 

3rd 

10 

c.  c. 

--  139-139.5° 

4 th 

10 

c.  c. 

— I39.5-I400 

5 th 

10 

c.  c. 

--  140-140.5° 

6 th 

10 

c.  c. 

— 140.5-140.5° 

7th 

10 

c.  c. 

--  140.5-141° 

8th 

10 

c.  c. 

•-  141-141.5° 

9 th 

10 

c.  c. 

- 141.5-142° 

10th 

10 

c.  c. 

..  142-144° 

No  residue. 

This  distillation  was  carried  out  more  to  satisfy  all  doubt 
as  to  the  limiting  values  of  the  boiling  range  of  the  origlonal. 


1 


19. 


so  that  it  could  confidently  assumed  that  all  of  the  substances 
obtained  were  actually  synthesized  and  not  contained  in  the 
original  . This  was  specially  true  of  the  small  amounts  of 
substance  boiling  directly  above  xylene  which  were  obtained. 

4.  Senaral  Appearance  of  Compounds.  The  original  oil  was  a 
moderately  thick, black, fluid  tar  much  resembling  crude  tar  oil 
in  appearance.  The  fractions  from  xylene  to  200®  were  almost 
water  white  and  had  an  odor  like  xylene.  From  200®to  250®  the 
oils  were  just  faintly  yellow, but  their  viscosity  was  greater 
and  they  smelled  distinctly  of  napthalene( after  long  standing 
small  amounts  of  napthalene  settled  out).  From  250*^  to  300®  the 
oils  were  a reddish  yellow  by  transmitted  light  and  light  green 
by  reflected  light, in  other  words  they  were  fluorescent  to  a 
slight  extent.  From  300®to  350®  the  oils  were  increasingly 
viscous  and  strongly  fluorescent, the  solids  which  occurred  here 
were  a bright  golden  yellow  in  color.  The  fraction  boiling  from 
350®  to  400®  was  a very  heavy, dark  green  oil, and  the  solids 
were  still  the  bright  yellow  spoken  of  before.  The  final  dist- 
illation products  were  a thick  paste, not  unlike  vaseline, which 
could  not  be  crystallized  even  by  an  ice-salt  bath, but  became 
almost  glassy  in  hardness.  Some  reddish  solids  were  present  in 
small  quantities  in  this  oil, and  the  final  distillation  product 
was  a red  solid  merging  to  a green  solid, and  finally  a mass  of 
what  proved  to  be  free  carbon  with  small  amounts  of  the  latter 
solids, which  came  over  just  before  coking  occurred. 

5.  Determination  of  Behavior  Toward  Solvents.  First  the  fraction 
boiling  from  300-350®  was  taken  for  separation  as  it  was  a 

large  fraction  and  obviously  consisted  of  at  least  two  substances. 


20. 


A method  of  hydrocarbon  separation  recommended  in  the  literature, 

1 ft 

was  by  fractional  recrystallization  from  alcohol  and  it  was 
thought  that  it  might  be  of  service  here.  This  straight  recryst- 
allization from  alcohol , although  it  finally  yielded  a substance 
with  a definite  melting  point (after  twelve  recrystallizations) 
was  finally  abandoned  as  worthless, as  the  amount  of  solvent  used 
was  altogether  out  of  proportion  to  the  results  obtained, and  as 
it  was  later  proved, the  same  substance  could  be  obtained  in  a 
purer  state  by  a much  simpler  process. 

This  solid  had  a melting  point  of  t 97^, and  on  oxidation 
yielded  a gummy  mass  which  was  impossible  to  obtain  in  crystalline 
form.  A single  recrystallization  from  hexane  brought  the  melting 
point  up  to  202°  where  it  remained.  The  alcohol, on  attempting 
to  recover  it  from  the  mother  liquors  was  found  to  be  unfit  for 
further  use, owing  to  a small  amount  of  oil, which  was  volatile  in 
alcohol  vapor, being  present.  Diluting  the  alcohol  gave  a milky 
emulsion, but  efforts  to  recover  this  oil  by  fractioning  the 
alcohol  proved  fruitless  due  to  the  volatile  nature  of  the  oil 
and  the  small  amounts  of  it  present. 

Abandoning  special  methods  for  the  moment, a portion  of  the 
origional  run  was  tested  with  certain  solvents  to  effect  a 
group  separation  if  there  were  more  than  one  group, or  if  only 
one, to  determine  the  position  of  this  group.  There  were  no  water 
soluble  constituents, so  phenols  are  absent.  Except  for  particles 
of  free  carbon, the  mass  was  entirely  soluble  in  ether  . Dilute 
hydrochloric  acid  had  no  solvent  action, and  dilute  potassium 
hydroxide  was  likewise  without  effect.  This  definitely  eliminated 
phenolic  substances  of  all  kinds.  Sulphuric  acid  had  no  action 


21. 


3 

in  the  cold, but  dissolved  the  whole  mass  on  heating.  This  last 
fact  indicates  the  presence  of  aromatic  or  unsaturated  aliphatic 
hydrocarbons. 

It  is  thus  seen  that  the  solubility  reactions  as  generally 
employed  gave  nothing  but  negative  information.  It  eliminated  the 
possibility  of  acidic, basic, phenolic , and  in  fact  everything  but 
aromatic  hydrocarbons , unsaturated  aliphatic  hydrocarbons, and 
halogen  derivatives  of  these.  The  preliminary  analysis  showed 
an  absence  of  halogens  so  the  search  v/as  confined  to  the  first 
two  types  of  substances  mentioned  exclusively. 

To  be  doubly  sure  that  there  were  not  small  amounts  of  sat- 
urated aliphatic  hydrocarbons  which  had  escaped  detection  before, 
three  ten  cubic  centimeter  portions  of  the  run  were  now  tested 
for  saturated  aliphatlcs.  One  of  these  portions  was  the  original 
tar  oil, another  was  from  the  light  oils, and  the  third  from  the 
heavy  oils.  They  were  placed  in  three  Babcock  testing  bottles 
and  thirty  cubic  centimeters  of  concentrated  sulphuric  acid  v/as 
added  to  each.  They  were  then  heated  on  the  steam  bath  at  a temp- 
erature of  100®  for  one  hour.  After  cooling  somewhat, the  bottles 
were  filled  with  the  same  concentrated  acid  up  to  the  graduated 
neck  and  centrifuged  for  five  minutes.  If  any  saturated  aliphatlcs 
were  present  they  would  appear  in  the  necks  of  the  bottles  and 
could  be  read  off  directly  in  fractions  of  a centimeter.  Careful 
examination  of  the  liquid  in  the  necks  of  the  three  bottles 
showed  no  oily  layer, and  saturated  aliphatic  hydrocarbons  were 
thus  shown  to  be  completely  absent. 

Alcohol  extraction  in  the  cold  appeared  to  effect  a fairly 
good  separation  of  the  oils  from  the  solids  in  the  high  boiling 


22. 


mixtures, and  leave  a mass  of  greenish  yellow  crystals  of  a fair 
degree  of  purity.  On  recovering  the  alcohol  by  distillation, it 
was  noticed  that  on  chilling  the  concentrated  liquors  at  inter- 
vals,a dark  brown, pitchy  mass  separated  out.  A considerable 
amount  of  this  substance  was  obtained, and  it  was  noticed  that 
the  same  yellow  crystals  came  out  of  solution  on  standing. 
Distilling  this  oil  under  diminished  pressure  gave  a clear, heavy 
oil, which  likewise  gave  a batch  of  yellow  crystals  on  standing. 

The  net  result  of  these  attempts  seemed  to  show  that  separation 
of  the  liquids  from  the  solids  by  fractional  precipitation  from 
alcohol  was  possible, but  incomplete  and  tedious. 

The  combined  residues  were  then  tested  with  carbon  tetrachlor- 
ide. It  was  entirely  soluble, and  no  separation  was  effected. 

Hexane, or  petroleum  ether  was  next  tried. This  would  remove 
phenanthrene  if  any  of  this  substance  were  present.  The  Hexane 
dissolved  out  all  of  the  liquids  and  left  a mass  of  bright  green 
crystals.  These  were  later  purified  still  more  by  recrystallizing 
from  acetone, and  identified.  On  recovering  the  hexane  the  same 
pitchy  mass  was  left  as  a residue. 

In  recrystallizing  the  solids  present  in  the  materials  studied 
it  was  Invariably  found  that , regardless  of  the  solvent  used,  the 
first  batch  of  crystals  were  greenish  in  color, and  the  second 
batch  pure  white, or  nearly  so.  This  seemed  to  indicate  the  pres- 
ence of  a persistent  impurity  whose  relative  solubility  in  a 
majority  of  solvents  was  less  than  the  accompanying  substances. 
The  amount  of  this  substance  was  never  great  enough  to  change  the 
melting  point  of  the  compound  by  an  amount  that  could  be  detected 
with  the  thermometer  used, as  two  samples  obtained  from  the  same 


23. 


solution, one  colored  and  the  other  colorless, both  had  exactly 
the  same  melting  point.  In  spite  of  this  it  was  assumed  that 
two  different  substances  were  present, and  this  actually  proved  to 
be  the  case  in  one  instance  where  the  a and  b methyl  anthracenes 
were  found  in  intimate  mixture. 

Many  other  solvents  were  tried  on  small  samples, benzene, 
xylene, acetone, acetic  acid, absolute  alcohol , carbon  disulfide, 
chloroform  and  ether  among  these, but  mostly  without  re suit, or 
with  results  which  were  no  better  than  those  already  tried.  A 
few  combinations  met  with  success  and  will  be  mentioned  again 
in  connection  with  identification.  The  results  from  the  applic- 
ation of  general  solvent  methods  were  negative, as  far  as  isolat- 
ing any  pure  compounds  were  concerned.  The  group  solubilities 
and  elementary  analysis  eliminate  everything  but  aromatic 
hydrocarbons  and  unsaturated  aliphatic  hydrocarbons.  Testing 
a portion  of  the  origional  run  with  neutral  potassium  permanganate 
in  dilute  alkali  solution  gives  a permanent  green  solution  with 
no  reduction  of  the  permanganate.  This  eliminates  the  unsaturated 
aliphatic  compounds, so  the  substances  may  be  assumed  to  be  purely 
aromatic  hydro carbons, and  subsequent  treatment  should  be  guided, 
to  a great  extent, by  experience  and  observation  during  the  course 
of  the  investigation. 

Separation  of  liquids  from  solids.  After  fractional  distill- 
ation,the  fractions  were  allowed  to  stand  for  some  time; so  that 
an  equilibreum  might  be  reached  between  the  suspended  solids  and 
the  liquids.  It  was  found  that  if  filtration  was  attempted  soon 
after  distillation  , solids  continued  to  settle  out  of  the 
liquid  afterwards, and  subsequent  filtration  was  necessary.  The 


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24. 


crystals  were  larger  on  standing, and  contained  less  occluded 
liquid.  The  scheme  followed  was  to  allow  the  fractions  to  stand 
for  a minimum  of  two  weeks  after  distillation, and  then  to  filter 
under  vacuum  at  room  temperature, and  Subjecting  the  liquids 
obtained  to  a freezing  mixture  of  ice  and  salt  for  several  hours 
and  repeating  the  filtration.  This  was  done  for  all  of  the  fract- 
ions in  which  the  liquids  were  capable  of  passing  through  common 
filter  paper  at  the  vacuum  available.  Melting  points  on  the  crude 
substances  first  filtered  off, and  those  subsequently  frozen  out 
and  filtered  off,  showed  considerable  variation, the  latter  being 
usually  lower  than  the  former.  Recrystallization  showed  that 
they  were  the  same  substance, and  that  the  initial  apparent  diff- 
erence was  due  to  the  varying  amounts  of  occluded  oils. 

The  products  of  the  fractional  distillation  were  thus 
roughly  divided  into  two  parts, the  liquids  and  the  solids, which, 
in  general, agreed  quite  closely  in  every  way  to  similar  fractions 
obtained  in  the  process  of  coal  tar  distillation. 

7 • Isolation  of  Compounds  Possible  by  Solubility  Behavior.  There 
are  several  compounds  v^hose  presence  was  suspected, and  later 
proven, that  are  capable  of  removal  by  solubility  methods.  These 
separations  by  solvents  follow  conventional  lines, although  there 
are  a few  slight  diversions  followed  which  seemed  to  give  good 
results. 

The  isolation  of  anthracene  by  solubility  difference  in 
coal  tar  naptha  and  acetone  was  followed  with  success.  The 
solids  filtered  from  the  fractions  boiling  from  290°  to  360°  were 
extracted  in  the  cold  v/ith  hexane, then  with  hot  hexane  after 
which  it  was  filtered  and  washed  with  the  same  solvent.  The 


25. 

solids  were  dissolved  in  hot  acetone, crystallized  out, and  filter- 
ed. These  crystals  were  recrystallized  three  times  from  benzene, 
after  which  the  melting  point  v/as  constant  at  215°.  It  was  pure 
white  with  a light  green  tinge  by  reflected  light.  It  was  identi- 
fied later  by  oxidation  to  anthraquinone. 

Phenanthrene, supposedly , is  in  the  hexane  mother  liquors, and 
by  concentration  it  may  be  obtained  in  an  impure  form.  This  was 
done, and  the  resulting  mass  dissolved  in  alcohol.  This  solution 
was  concentrated  and  the  first  and  second  batch  of  crystals 
obtained  discarded.  Finally  it  was  evaporated  down  to  small 
volume  and  chilled.  A mass  crystallized  out,ancj^had  a melting 
point  of  98°.  Recrystallization  from  benzene  raised  this  to 
99^, it  was  a white  solid  without  fluorescence. 

Pyrene, if  present, is  in  the  solids  distilling  above  360°, 
and  may  be  separated  from  these  by  extraction  with  carbon  disulf- 
ide. The  carbon  disulfide  solution  is  evaporated  to  dryness, the 
residue  dissolved  in  hot  alcohol  and  a hot  alcoholic  solution  of 
picric  acid  is  added.  The  picrate  fomed  is  repeatedly  recryst- 
allized from  alcohol  and  finally  decomposed  with  ammonia.  The 
resulting  compound  is  pyrene.  The  identification  was  somewhat 
difficult, but  was  finally  accomplished  successfully. 

Chrysene  is  left  behind  on  extraction  with  carbon  disulfide, 

and  it  may  be  crystallized  from  hot  glacial  acetic  acid.  This  was 

done  to  the  black  particles  left  by  the  carbon  disulfide  and  a 

very  small  amount  of  very  green  crystals  were  obtained  which 
o 

melted  at  250  exactly, but  further  identification  was  impossible 
due  to  the  small  amount  obtained. 

The  large  quantities  of  the  solids  which  were  intermediate 


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26. 


in  solubility  between  anthracene  and  phenanthrene  were  next 
examined  and  recrystallized  from  acetone.  The  first  batch  of 
crystals  were  discarded  to  remove  the  last  traces  of  anthracene, 
and  the  second  batch  taken  and  recrystallized  from  alcohol  until 
a constant  melting  point  was  reached  at  202°.  This  same  substance 
was  obtained  from  other  solutions  in  considerable  quantities. 

It  wa,s  noticed  that  the  substance  seemed  to  have  a transition 
point  at  about  110°,  and  a considerable  portion  of  it  sublimed 
to  the  sides  of  the  tube.  A survey  of  the  literature  left  little 
doubt  that  this  was  b-methyl  anthracene , and  the  presence  of  this 
hydrocarbon  was  fully  confirmed  later. 

8.  Steam  distillation  of  liquids  and  solids.  In  the  scheme  of 
separation  the  substances  were  first  distilled, and  then  steam 
distilled.  The  fractions  were  distilled  in  a current  of  steam  in 
their  regular  order, the  oils  coming  over  being  water  white, and 
of  a specific  gravity  noticably  less  than  before  steam  distillat- 
ion. This  was  due  to  a high  boiling  residue  which  was  relatively 
non-volatile  in  steam  which  remained  behind  in  the  flask.  In  the 
lowest  boiling  f raction^which  origionally  had  a yellowish  color^ 
this  high  boiling  constituent  was  present  to  some  extent, and  an 
increasingly  great  amount  of  it  collected  as  the  distillation 
progressed.  This  was  of  considerable  interest, and  as  it  was 
noticed,  a good  separation  of  the  heavy  non-volatile  liquids  was 
effected  in  this  manner, which  was  possible  in  no  other  way,  as 
they  were  dispersed  in  considerable  quantities  throughout  the 
whole  range  of  the  preliminary  distillation  products.  The  oils 
thus  obtained  were  carefully  dried  and  fractioned  again.  This 
time  they  distilled  over  practically  colorless, and  many  of  the 


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27. 

previous  fractions  were  found  to  boil  at  the  same  point  now  that 
the  non-volatile  oil  had  been  removed.  Many  constant  boilin;^ 
fractions  were  found , naptha lene  was  completely  separated  from 
its  accompanying  oils, and  diphenyl, the  presence  of  which  had 
defied  detection  previously  was  obtained  in  small  amounts  from 
the  250-260°  fraction.  During  the  last  stages  of  the  steam 
distillation  a small  amount  of  a vfhite  solid  appeared  in  the 
very  last  portion  of  the  oil  which  was  capable  of  being  driven 
over  by  steam.  It  had  a melting  point  of  141°.  The  steam  distill- 
ation brought  out  another  interesting  fact  in  that  it  showed 
conclusively  that  the  fractions  obtained  from  145°  to  210°  were 
but  a mixture  of  the  xylenes  and  the  heavy  liquid  mentioned 
before, for  on  distilling  the  oil  after  steam  distilling  it  was 
found  that  it  all  boiled  under  150°, and  that  from  150°to  210° 
there  was  a gap  in  which  but  a few  centimeters  of  oil  were  ob- 
tained. The  residue  oil  from  the  steam  distillation  was  dried 
and  chilled  in  a freezing  solution.  A small  amount  of  solids 
separated  out  and  were  removed  by  filtration  with  strong  suction. 
An  attempt  was  next  made  to  distill  this  oil  under  diminished 
pressure.  At  a vacuum  of  seventy  five  centimeters  of  mercury  and 
a temperature  of  320-330°Centigrade  a small  amount  of  the  oil 
was  distilled, but  as  there  was  considerable  amounts  of  a solid 
which  crystallized  out  of  the  cold  oil, and  also  because  the  oil 
foamed  badly  during  distillation, it  was  thought  that  it  was 
partially  decomposed  even  at  the  vacuum  used, and  the  distillation 
was  discontinued.  The  oil  wa,s  red  with  a strong  green  fluorescence, 
and  of  a syrupy  consistency. 

Some  of  the  liquid  fractions  which  boiled  through  a range  were 


28. 

subjected  to  a current  of  alcohol  vapors  applied  in  the  same 
manner  as  steam  in  a steam  distillation.  The  condensate  was  then 
f ractioned,but  the  oils  thus  carried  over  were  insi^^nif icant . The 
alcohol  used  was  absolute, and  of  constant  boilinc;  point.  The 
passing  of  ether  vapors  through  the  oils  conducted  in  the  same 
apparatus  was  equally  barren  of  results. 

9.  Special  Methods  of  Purification.  The  solids  melting  between 
1 99° and  202°  were  thought  to  be  a mixture  of  a and  b methyl 
anthracenes, and  their  separation  was  despaired  of  until  use  was 
made  of  the  property  of  the  beta  variety  of  subliming  at  100°  or 
over.  The  mixture  was  heated  to  120°  and  a current  of  air  direct- 
ed against  it  and  carried  off.  A mass  of  silky  crystals  were 
deposited  on  the  walls  of  the  discharge  tubes  and  thus  a fairly 
complete  separation  was  effected. 

In  all  cases  but  this  one, recrystallization  from  solvents  was 
employed  as  the  final  stage  in  the  purification  of  the  substance, 
liquids, of  course, are  likewise  excepted. 

The  napthalene  crystallized  out  of  the  oils  in  quantity, and 
was  obtained  by  simple  filtration, although  a portion  was  recryst- 
allized from  alcohol  for  the  making  of  derivatives. 

The  diphenyl  was  frozen  out  of  the  250-265°  fraction  of  the 
oils, and  filtered  off  with  some  difficulty, as  the  slightest 
temperature  rise  caused  it  to  go  back  into  solution  and  escape 
through  the  filter.  The  quantity  obtained  was  so  small  that  it 
was  merely  pressed  dry  and  identified  without  further  purific- 
ation. 

These  are  representative  of  the  methods  employed  in  isolating 
the  substances  identified, so  further  elaboration  is  unnecessary. 


30. 


in  cold  carbon  tetrachloride  solution, althou/a;h  on  heating 
bromine  was  absorbed  in  nearly  every  case  with  evolution  of 
hydrobromic  acid. 

12.  Specific  tests  and  Choice  of  Derivatives  to  be  Made.  Specific 
tests  in  almost  every  case  involved  the  making  of  a derivative, as 
these  specific  tests  were  usually  oxidation  reactions, reactions 
with  picric  acid, or  with  FeCl^,so  the  derivative  chosen  was  one 
which  would  be  produced  as  a result  of  a specific  test  whenever 
possible. 

The  derivatives  were  usually  quinones  or  acids, obtained  by 
oxidising  a small  quantity  of  the  hydrocarbon  with  chromic  acid 
in  boiling  glacial  acetic  acid  solution.  The  product  was  filtered 
and  the  chromic  acid  washed  out  with  distilled  wa.ter,and  then 
recrystallizing  the  product  from  absolute  alcohol. 

The  fact  that  most  hydrocarbons  combine  with  picric  acid  to 
forra  characteristic  derivatives  was  taken  advantage  of  in  some 
cases.  The  picrates  are  solids, but  often  are  unstable  on  heating 
or  in  the  presence  of  moisture; so  their  use  was  avoided  as  much 
as  possible.  They  have  the  advantage  of  being  easily  made  and 
purified, the  picrate  settling  out, on  cooling,  of  a hot  alcoholic 
solution  of  the  hydrocarbon  and  picric  acid.  They  are  easily 
recrystallized  from  the  same  solvent. 

Diphenyl  was  most  easily  identified  by  the  making  of  the  mono- 
brom  derivative. 

13.  Hydrocarbons  Identified  in  Straight  Xylene  Runs.  Napthalene, 
CiqHsjM.P. 809. ,was  the  first  hydrocarbon  isolated  from  the  strai- 
ght xylene  runs.  Due  to  the  fact  that  the  napthalene  samples  had 
been  run  through  the  furnace  prior  to  the  time  the  xylene  was  run, 


\ 


29. 


10.  Accurate  Determination  of  Physical  Constants.  Meltinc^  points 
were  taken  in  a special  apparatus  designed  so  that  uniform  temp- 
erature is  maintained  by  convection  currents, making  stirring  by 
hand  unnecessary.  In  this  device  the  thermometer  was  fitted'  with 
a cork  stopper, into  a tube  about  the  size  and  diameter  of  a test 
tube, but  which  had  a U shaped  side  arm.  On  heating  the  side  arm, 
the  liquid  inside ( sulphuric  acid  in  this  case)  rises  into  the  test 
tube  and  the  cooler  liquid  descends  into  the  lower  portion  of  the 
side  arm  and  is  heated.  This  method  has  the  advantage  of  minimum 
stem  exposure, good  control  of  temperature, ease  of  handling,and 
speed  of  operation. 

Boiling  points  were  determined  with  an  accurate  Centigrade 
thermometer  immersed  in  the  vapor  of  the  substance. 

Specific  gravities  of  the  liquids  were  taken  with  a 1 c.ol 
pyknome ter, which  was  maintained,during  use, at  a constant  temp- 
erature of  15-5°Centigrade. 

The  constants  of  the  substances  identified  will  be  mentioned 
in  connection  with  the  complete  identifications  given  in  detail 
later, so  they  need  not  be  discussed  here  with  the  methods  used 
in  obtaining  them. 

1 1 .Application  of  Class  Reactions.  Hydrocarbons  of  such  closely 
related  nature  naturally  exhibit  similar  class  reactions.  They  all 
give  the  characteristic  reactions  for  aromatic  hydrocarbons , as 
well  as  some  fairly  well  defined  color  reactions  with  certain 
reagents, but  as  these  are  considered  unreliable, they  were  not  used 
at  all  in  this  work.  The  tests  for  aromatic  hydrocarbons  gave 
positive  results  in  all  cases.  Dimethyl  sulphate  reacted  in  the  cold 
with  most  of  the  liquids, but’ in  no  case  did  they  absorb  bromine 


31. 


it  was  thoup;ht  that  the  occurrence  of  napthalene  at  this  point 
mi^ht  be  due  to  a small  amount  which  had  lod/a;ed  in  the  furnace 
and  later  was  carried  over  with  the  xylene  vapors.  A succeeding 
run  made  with  a new  furnace  lining  and  new  catalysts  revealed 
napthalene  in  the  same  proportions ; so  it  was  concluded  that  it  was 
actually  formed  during  the  run.  This  is  of  considerable  theor- 
etical interest, as  no  evidence  was  found  that  its  synthesis  had 
been  preformed  previously  in  this  manner, and  from  xylene.  It  also 
adds  to  the  proof  obtained  that  the  xylene  molecule  is  broken 
down  during  the  run.  It  was  separated  by  fractional  distillation, 
and  appeared  only  in  the  oils  boiling  between  230°and  245?. After 
steam  distilling  and  then  fractioning, the  napthalene  boiled  at 
the  proper  temperature, between  210°and  225°.  Aportion  of  the  total 
amount  frozen  out  of  the  oil  was  recrystallized  from  alcohol, and 
the  melting  point  determined.  It  was  exactly  at  80°.  The  picrate 
was  made  and  was  found  to  melt  at  150-151°  which  was  the  melting 
point  given  for  napthalene  picrate.  Although  its  characteristic 
odor  and  appearance  would  almost  serve  to  identify  it, the  usual 
care  was  taken  in  the  complete  identification  because, as  mention- 
ed before, its  presence  was  not  expected, and  its  appearance  in  such 
large  quantities  was  quite  a surprise. 

The  next  compound  to  be  identified  was  b-methyl  anthracene, 
4H^CH^,M.P. 202°. , and  seemed  to  be, together  with  a-methyl  anth- 
racene, the  most  abundant  compound  in  the  tar.  After  extracting 
the  anthracene  fraction  with  hexane, it  was  noticed  that  the 
hexane  dissolved  out  almost  all  of  the  solids  present , leaving 
but  a small  residue.  These  dissolved  solids  were  recovered  and 
purified, but  it  was  impossible  to  obtain  a sample  with  a definite 


I 

f 


32. 


melting  point  by  ordinary  recrystallization.  Assuming  that  the 
specimen  under  consideration  had  some  b-raethyl  anthracene  in  it, 
and  knowing  of  the  manner  in  which  it  sublimes  at  low  temperatures 
sublimation  in  a current  of  air  was  tried, and  proved  very 
successful.  A fluffy  mass  of  needle-like  crystals  were  formed 
which  melted  sharply  at  202®.  The  pi crate  was  made, but  it  was 
unstable  and  no  melting  point  could  be  obtained.  Next  oxidation 
was  attempted  in  acetic-chromic  a,cid  solution, and  after 
prolonged  oxidation  a substance  v/as  formed  which  on  recrystalliz- 
ation from  alcohol  gave  a mass  of  straw  colored  needles  which 
melted  at  262-263°,and  were  soluble  in  strong  alkali.  This 
was  the  b-anthracene  carbonic  acid. 

In  the  sublimation  residues  the  a-methyl  anthracene , C 1 4H^CH^ , 
M.P.205^,was  thought  to  be  left.  Since  it  still  contained  small 
quantities  of  the  b product, it  was  recrystallized  from  acetone 
several  times, the  second  batch  of  crystals  being  taken  in  each 
case  until  the  product  melted  exactly  at  204®.  On  oxidation  this 
gave  a substance  which  melted  almost  were  the  origional  hydrocar- 
bon mel ted, 205- 207° , but  this  was  soluble  in  strong  potassium 
hydroxide  solution  so  it  was  concliided  to  be  the  a-anthracene 
carbonic  acid,M.P. 206®. 

Anthracene  was  present  in  small  amounts.  About  five  grams 
of  it  appeared, after  long  standing, in  the  oils  boiling  from  225- 
300®, and  it  was  also  separated  in  some  quantity  by  solubility 
as  described  before.  The  product  identified  was  recrystallized 
from  benzene  and  had  a M.P.  213°.  On  oxidation  in  the  usual  manner 
it  gave  anthraquinone,M. P. 278-280®.  This  was  given  the  usual  test 
for  anthraquinone , by  alkaline  reduction  with  zinc  dust  and 


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33 


dilute  potassium  hydroxide , and  gave  the  transient  red  color, 
disappearing  on  shaking. 

On  subjecting  the  oils  boiling  from  251°to  271^^  to  a freezing 
mixture, a mass  of  white  crystals  appeared, which  were  filtered 
quickly  and  clay  plated.  This  was  diphenyl, (C5H5)2, M.P. 70°.  A 
single  recrystallization  from  a few  c.c.  of  alcohol  gave  a 
product  which  melted  sharply  at  70®  and  was  practically  odorless. 
Bromination  in  the  presence  of  iron  was  tried, but  no  derivative- 
could  be  separated.  A small  amount  was  dissolved  in  carbon  disul- 
phide and  bromine  added  in  the  cold.  Concentration  of  this 
solution  gave  a brown  solid  which  had  a melting  point  of  302-5® 
and  it  was  assumed  to  be  the  p-brom  derivative  of  diphenyl, 

M. P.310®. 

The  a and  b methyl  napthalenes,C^^H^CH^  B. P. 1 40- 1 42°, 1 41 - 
143°, were  next  identified.  In  the  oils  which  boiled  from  240®to 
250®  it  was  noticed  that  on  placing  in  an  ice  salt  solution  the 
oil  congealed  to  an  opaque, white  mass, which, on  attempting  to 
filter, dissolved  again  into  the  accompanying  oil  and  passed 
through  the  filter.  This  occurred  repeatedly  despite  all  pre- 
cautions to  have  both  the  filter  and  solution  as  cold  as  possible. 
The  slightest  current  of  v/arm  air  dissolved  the  substance. 

The  oil  was  ref ractioned,and  only  the  fraction  boiling  between 
240®  and  245®  was  taken  for  consideration, as  this  was  assumed  to 
contain  the  major  portion  of  the  a and  b methyl  napthalenes 
suspected  to  be  present. B-methyl  napthalene  melts  at  37^  while 
a-methyl  napthalene  does  not  solidify  until  -22°  is  reached, but 
their  solubilities  one  in  the  other  are  ao  complete  that  this 
difference  in  melting  point  could  not  be  utilized  in  separating 


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34. 


these  substances.  Their  boiling  points  are  practically  identical, 
so  they  cannot  be  fractioned  from  each  other.  The  picrates  of 
each  of  these  substances  melt  at  the  same  point , 1 15* 5^ , and  a 
picrate  made  of  the  mixture  was  seen  to  melt  somewhat  below  this 
temperature, 1 12-1 13®.  The  two  oils  have  the  same  specific 
(3;ravity ; 1 . 001  ,and  a specific  s^ravlty  determination  made  on  the 
mixed  oil  gave  exactly  this  value  at  15*5®Centigrade.  The  two 
isomers  were  then  assumed  to  be  present  in  a mixture  which  was 
inseparable  by  ordinary  means. 

In  the  middle  fractions  of  oil, the  fractions  boiling  from 
270®  to  280°  was  suspected  to  consist  largely  of  the  mixed  di- 
tolyls ,CH3CgH^-C5H^CH^,275“280® . These  substances  all  oxidise  to 
isophthalic  acid, so  their  presence  could  be  collectively  proven 
by  this  oxidation.  It  was  not  so  simply  carried  out, since  these 
oils  seem  to  resist  oxidation  by  chromic  acid  in  glacial  acetic 
acid  to  a remarkable  degree, but  after  prolonged  boiling  under 
reflux, a product  was  obtained, which  on  recrystallization  from 
benzene  gave  a melting  point  of  295®.  This  was  soluble  in  hot 
alkali  and  was  assumed  to  be  the  isophthalic  acid  derivative. 

The  remainder  of  the  oils  were  assumed  to  be  a mixture  of 
the  dimethyl  napthalenes, and  careful  fractionation  gave  a portion 
boiling  from  262-264® , which  gave  a picrate  in  alcoholic  solution 
consisting  of  bunches  of  orange  colored  needles  which  melted  at 
138°.  The  picrate  of  1,2, dimethyl  napthalene,B.P. 262-4®, is  said 
to  melt  at  139®, and  this  hydrocarbon  was  present  in  considerable 
quantity  with  its  other  i somers , which  were  not  identified. 

Phenanthrene ,C-j 4H|Q,M.P.  100® ,was  assumed  to  be  present  on 
account  of  the  presence  of  dltolyls  from  which  it  may  be  formed 


35. 


by  simple  reduction , but  as  with  anthracene, only  an  extremely  smal] 
amount  was  isolated.  It  was  obtained  from  the  hexane  mother  liqu- 
ors after  the  anthracene  and  methyl  anthracene  was  removed.  It 
had  a melting  point  of  96^  and  after  an  attempt  at  oxidation 
which  yielded  only  a pasty  mass, the  picrate  was  made  from  benzene 
solution  and  had  a melting  point  of  141-143°.  The  melting  point 
of  the  picrate  given  in  the  literature  is  145®. 

Attention  was  now  given  to  the  high  boiling  solids  which 
came  over  Just  before  coking.  These  were  orange  colored  crystals 
merging  to  a dark  green  toward  the  very  last.  These  green  cryst- 
als corresponded  in  every  way  to  chrysene  as  described. in  the 
literature , and  as  this  substance  is  relatively  insoluble  in 
carbon  di sulfide , the  mass  wa,s  dissolved  in  the  smallest  a,mount 
of  this  solvent  possible.  It  all  passed  into  solution, but  on 
standing  for  several  days  a heavy  black  residue  settled  out  of 
the  carbon  disulphide  solution,.  which  was  filtered  off.  There 
was  but  a trifling  amount  of  this, but  it  was  dissolved  in  a few 
cubic  centimeters  of  benzene  and  recrystallized.  A small  quantity 
of  transparent  crystals  were  obtained  which  on  filtering, colored 
the  filter  a deep  green.  There  was  Just  enough  for  a melting 
point  which  was  255°.  Chrysene, Ci3Hi2»M.P250®  was  present  in 
extremely  small  quantity. 

The  carbon  disulphide  solution  was  then  evaporated  to  dry- 
ness, and  taken  up  with  alcohol, from  which  the  solid  obtained 
was  crystallized  several  times.  Pyrene ,C^ gH-j q,M  P.  148°, was  what 
this  solid  proved  to  be, its  melting  point  was  145-7°  and  a picrate 
made  melted  at  220°, which  checked  with  the  theoretical  M.P.222°. 

A pure  white  substance  which  had  a blue  fluorescence, distill- 


.0  iMKtft^ia>!wriii;ww>i 


36. 


ed  over  with  the  heavy  oils  during  steam  distillation.  This  had 
a melting  point  of  140-141°  when  impure, but  on  recrystallization 
from  benzene  the  melting  point  rose  to  2 13^, where  it  remained 
stationary  after  another  recrystallization.lt  was  assumed  to  be 
a very  pure  form  of  anthracene , which  had  appeared  at  two  other 
points  in  the  investigation, and  had  been  identified , so  no  fur- 
thur  identification  was  made, as  the  amount  wa,s  too  small. 

These  are  all  of  the  substances  identified  in  the  straight 
xylene  runs  and  undoubtedly  they  make  up  a major  portion  of  the 
total.  There  are, without  doubt, many  compounds  present  in  small 
quantities  which  entirely  escaped  detection.  The  oils  from  which 
the  diphenyl  was  obtained  might  contain  ethyl  napthalenes  and 
methyl  diphenyls, but  no  further  attempt  was  made  to  identify 
any  compounds  at  this  point.  The  higher  fractions, from  280-2go? 
from  the  results  of  previous  investigators , was  thought  to  be 
largely  diphenyl  ethane, and  there  was  a possibility  of  mesitylene 
being  present  in  the  small  quantities  of  oil  obtained  from  the 
fractions  distilling  between  xylene  and  napthalene, although  this 
possibility  was  lessened  by  the  course  taken  by  the  breaking  down 
of  hydrocarbons  in  pyrogenetic  decomposition.  According  to  the 
most  generally  accepted  theory  the  high  benzene  homologues  are 
the  first  to  decompose, so  mesitylene  would  not  be  formed  here  at 
all, or  if  formed  momentarily , would  be  decomposed  as  fast  as  formed 
in  the  furnace.  The  latter  is  probably  the  case. 

14.  Hydrocarbons  in  the  Xylene-Ethylene  Runs.  The  hydrocarbons 
formed  in  this  series  of  runs, in  general , comprised  the  same 
sub stances, and  were  separated  according  to  the  same  scheme  as 
those  in  the  straight  xylene  runs.  Napthalene  was  formed  in 


57. 


considerable  quantity, but  its  identity  being  obvious, no  tests  were 
made  upon  it.  Diphenyl  was  produced  in  about  the  same  quantity  as 
in  the  former  case, and  was  identified  as  previously.  The  oils  were 
considerably  less  in  quantity  than  in  the  straight  xylene  runs, but 
the  solids  were  present  in  greater  proportion , thi s v/as  especially 
true  of  the  substances  which  distilled  over  360°.  Over  a gram  of 
pure  chrysene  was  isolated  from  the  fraction  distilling  just 
prior  to  coking.  It  was  a yellowish  white  solid  upon  recrystalliz- 
ation from  benzene, and  melted  sharply  at  250^,  Pyrene  was  present 
as  before  and  a small  quantity  of  a substance  melting  between  244*^ 
and  246°  was  found  with  the  pyrene  and  separated  from  it  by 
difference  in  solubility  in  alcohol.  This  was  oxidised  in  glacial 
acetic  acid  with  chromic  acid,a,nd  a product  obtained  which  melted 
at  178°  This  proved  the  original  compound  to  be  2, 3, dimethyl 
anthracene. 

Anthracene  was  present , though  as  before, in  surprisingly 
small  amounts, and  the  a and  b methyl  anthracenes  were  found  in 
large  quantity.  The  a and  b methyl  napthalenes  were  in  the  oils, 
as  was  1,2, dimethyl  napthalene, which  was  fractioned  and  identified 
by  making  the  picrate  as  before. 

All  indications  show  that  the  two  runs  were  essentially  of 
the  same  composition.  The  xylene-ethylene  product  contained  the 
solids  in  much  larger  proportion  than  did  the  straight  xylene 
products, so  it  was  possible  to  find  the  2,3  dimethyl  anthracene 
which  was  probably  present  in  small  quantity  in  the  straight  xylene 
r^on  as  well.  Chrysene  was  also  present  in  larger  amounts  as  well 
as  a very  small  quantity  of  a hydrocarbon  which  was  obtained 
pure  as  small . granul ar . bl a.ck  crystals  which  looked  like  powdered 


38. 


graphite.  This  had  a melting  point  of  255°and  in  glacial  acetic 
acid  solution  it  was  a dark  purple .without  fluorescence.  It  was 
insoluble  in  benzene  and  carbon  disulfide , but  soluble  in  glacial 
acetic  acid, from  which  it  was  recrystallized.  It  v/as  not  identi- 
fied, but  was  thought  to  be  chrysogene.a  compound  about  which 
very  little  is  known. 

15.  Manipulation  of  Napthalene  Run  Products.  These  samples  were 
principally  napthalene , so  the  first  thing  to  be  done  was  obvious- 
ly to  get  rid  of  this  napthalene  entirely.  Steam  distillation 
suggested  itself  immediately , and  the  five  samples  were  steam 
distilled  until  the  condensate  came  over  clear.  The  residues 
left  in  the  flask  in  every  case  looked  like  pitch  with  consider- 
able amounts  of  free  carbon  in  suspension.  After  trying  several 
solvent s , ether  was  fina,lly  decided  upon  as  it ' seemed  to  be  the 
most  efficient  in  dissolving  the  tarry  constituents  in  the 
product.  After  evaporation  of  the  ether  extract  a very  viscous 
reddish  oil  was  left  behind  in  every  case, but  the  combined 
oils  from  the  five  runs  did  not  exceed  three  cubic  centimeters, 
and  it  was  impossible  to  identify  it.  There  was  a solid  in 
suspension  in  this  oil  which  was  thought  to  be  benzerythrene , as 

its  appearance  and  the  manner  in  which  the  product  came  from  the 

4 

furnace, as  a'*bright  red  powder", all  bear  out  this  assumption  . 

It  was  not  identified. 

The  solids  left  by  the  ether  extraction  were  black  or  dark 
brown  in  all  cases, and  consisted  principally  of  amorphous  carbon. 
A suggestion  of  crystalline  structure  in  one  of  the  samples  led 
to  an  extraction  with  benzene, and  after  filtering  off  the  carbon 
and  concentrating  the  solution, a mass  of  pure  white  plates 


VT 


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39. 


crystallized  out.  These  were  filtered  off  and  identified.  The 
napthalene  which  had  been  steam  distilled  was  then  dried  and 
distilled  under  atmospheric  pressure  to  see  if  any  other  substance 
had  come  over  with  the  napthalene.  There  v/as  nothing, as  practically 
all  of  the  napthalene  boiled  at  the  desired  temperature, 2 12®. 

The  products  obtained  seemed  to  be  independent  of  the  carrier 
o;as, except  in  the  quantity  produced, as  all  of  the  runs  had  the 
same  composition. 

16.  Hydrocarbons  in  the  Napthalene  Runs.  The  oil  produced  was 
so  difficult  to  handle, and  so  small  in  quantity  that  nothinf?; 
was  identified  in  it. 

The  solid  produced  was  present  in  considerable  quantities, 
and  was  found  to  have  a sharp  meltinp;  point  at  189*^.  It  had  the 
same  melting  point  and  appearance  in  every  case  so  it  was  assumed 
to  be  the  same  substance  produced  in  each  run. 

It  was  first  thought  to  be  b-napthoic  acid , qH^COOH , as 
phthalic  acid  is  formed  in  a similar  pyrogenetic  decomposition, 
although  the  melting  point  was  quite  high  for  it.  Another  reason 
which  supported  this  view  of  the  presence  of  napthoic  acid  was 
that  it  was  formed  in  the  002'^^^'^  in  quantities  exceeding  the 
amount  produced  by  all  the  other  runs  put  together, and  its 
formation  could  be  easily  explained  by  the  simple  addition  of  a 
molecule  of  C02to  a molecule  of  napthalene.  A portion  of  it 
recrystallized  from  petroleum  ether  had  a constant  melting  point 
at  184°,  which  was  much  nearer  the  melting  point  of  b-napthoic 
acid (132®)  than  the  sample  obtained  from  benzene. 

This  theory  was  broken  down  at  once  when  it  was  found  that 
the  substance  was  insoluble  even  in  hot  concentrated  alkali. 


r 


( 


) 


i 


40. 


The  regular  procedure  was  then  resorted  to.  It  was  found  to  be 
a saturated  aromatic  hydrocarbon.  Consulting  the  literature , there 
was  finally  found  a hydrocarbon  which  seemed  to  fit  the  require- 
ments. It  was  b-b-dinapthyl , which  crystallized  in  plates, melted 
at  187*^, and  had  a stable  picrate  which  melted  at  183-4°.  The  pic- 
rate  was  made  in  benzene  solution  and  came  down  as  an  orange 
crystalline  precipitate , which  had  the  desired  melting  point, 132- 
184°. 

It  is  seen  that  dinapthyl  is  the  principal  product  formed 
in  the  pyrogenetic  decomposition  of  napthalene ,in  the  same 
manner  as  diphenyl  is  formed  in  the  thermal  decomposition  of 
benzene, a point  which, heretofore, had  not  been  touched  upon  in 
the  treatment  of  pyrogenetic  decompositions  of  hydro carbons. The 
a-a-dinapthyl  was  probably  formed  in  very  small  quantities, but 
it  escaped  detection. 

17.  Approximate  Yields  in  each  Case.  No  attempt  was  made  to  get 
quantitative  results  in  this  work.  Note  was  generally  taken  of  the 
relative  amounts  of  the  substances  present  in  each  case, and  for 
estimations  of  the  amounts  produced  in  proportion  to  the  amounts 
of  xylene  run  through  the  furnace, ref erence  must  be  made  to  the 
thesis  of  Dr. Bradley^ in  which  the  methods  of  formation  of  the 
tars  are  discussed  in  detail. 

Napthalene  was  formed  to  the  extent  of  about  5 to  7 percent, 
in  both  the  xylene  and  the  xylene -ethylene  runs, which  is  consider- 
ably higher  than  most  investigators  had  found  previously. 

The  oils  comprised  about  forty  percent  of  the  total  in  the 
case  of  the  xylene  run, and  was  about  one-half  that  amount  in  the 
case  of  the  ethylene  run. 


I 

' 5 


I 


■I 

4 


i 


41  . 

Anthracene  was  very  low  in  both  runs , certainly  not  over  two  or 
three  percent.  The  methyl  anthracenes  comprised  the  bulk  of  the 
solids  in  both  cases , amount  in/2;  to  about  one  third  of  the  total 
in  both  cases.  The  hi?2;h  boilinc^  tarry  constituents  containing 
the  pyrene  and  chrysene  were  present  in  small  amounts; in  the  case 
of  the  xylene  amountina;  to  perhans  five  percent. In  the  ethylene 
runs  they  were  much  higher  probably  near  twenty  percent. 

In  the  napthalene  runs, as  was  mentioned  before, the  single 
CO^  3:’un  contained  the  bulk  of  the  product.  The  nitrogen  sample 
came  next  with  about  one-third  of  this  amount, or  roughly, five 
grams.  The  hydrogen  and  one  CO  sample  contained  about  four  grams 
each, and  the  other  CO  sample  contained  less  than  one  gram. 

18.  Methods  of  Separation  Best  Adapted  to  this  Type  of  Hydrocarbon/ 
It  was  found, as  all  workers  in  the  separation  of  decomposition 
product  hydrocarbons  seem  to  agree, that  a preliminary  fractional 
distillation  was  essential.  Steam  distillation  was  next  tried 
with  considerable  success, as  it  divided  the  substances  present 
into  two  classes , those  volatile  vrith  steam  and  those  non- 
volatile. In  general, the  substances  having  two  benzene  rings  or 
under  in  each  molecule  distilled  in  a current  of  steam  quite 
readily.  Three  ring  compounds  were  found  to  be  almost  non- 
volatile,and  above  that  completely  non-volatile, as  the  clarity 
of  the  oils  testified.  In  the  preliminary  distillation  the  oils 
as  low  as  190^  were  a reddish  yellow  color  with  green  fluor- 
escence,but  after  steam  distillation  they  were  practically 
colorless  with  slight  opalescence.  The  anthracene  may  be  removed 
from  accompanying  substances  by  solvents  as  described, or  by 
direct  oxidation  of  the  fraction  as  obtained  with  chromic  acid 


f 1'  !:■  • 


\ ‘ ‘ ' 3.  1 fc/i<vVj^  • . 


J.W.'  .:j;,  ' '■'  .'■.,* 


N » • * «v ' • 


I. 


L_> 

* ^ ^ V,  ►«' 


I.  ^ 


JA'-i 


J 


^ . 1 


42. 


filtering  and  washing, sund  then  extro,cting  acidic  and  uanlc 
substances  by  treating  with  dilute  alkali  and  acid  successively. 
The  anthraquinone  resulting  may  be  reduced  back  to  anthracene 
or  used  as  obtained. 

Napthalene  crystallizes  out  of  its  accompanying  oils  on 
standing, and  may  be  filtered  off  direct  in  a fair  state  of 
purity. 

These  are  the  only  two  substances  produced  which  are  other 
than  of  scientific  interest, and  the  separation  of  the  other  sub- 
stances recommended  is  the  same  as  described  in  the  course  of 
the  study. 

In  the  case  of  the  napthalene  samples, the  method  of 
separation  was  more  or  less  a product  of  the"cut  and  try'* system, 
as  there  was  no  previous  work  done  along  these  lines  to  guide 
the  methods  used.  The  use  of  solvents  was  seriously  contemplated 
without  a preliminary  steam  distillation, but  fortunately  was 
not  attempted.  The  preliminary  steam  distillation  removed 
nothing  but  the  napthalene; this  was  proved  by  the  subsequent 
distillation  of  the  napthalene  obtained.  Various  solvents  were 
tried  on  the  tarry  substances  resulting  from  steam  distillation, 
but  none  of  them  were  as  satisfactory  as  the  common  ether 
finally  decided  upon.  The  dinapthyl  found  was  almost  insoluble 
in  cold  ether, but  quite  soluble  in  benzene, from  which  it  was 
later  recrystallized  . 

t9.  Some  Special  Aspects  of  the  problem.  A carbon  disulfide 
solution  of  the  origional  run, completely  free  of  solid  matter, 
v/as  found  to  give  a heavy, dark  brown, floe culent  precipitate 
on  pouring  into  a large  volume  of  petroleum  ether.  This, on 


43. 

filtering  was  found  to  have  a melting  point  of  1 00-1 05° • Having 
an  opportunity  to  examine  asphaltenes  obtained  from  G-ilsonite 
by  exactly  the  same  method ; precipitation  of  the  carbon  disulfide 
solution  with  petroleum  ether, it  was  noticed  that  it  agreed 
remarkably  with  the  natural  asphaltenes  in  appearance  and  melt- 
ing point.  Knowing  that  the  natural  asphaltenes  have  a high 
sulphur  content, and  knowing  that  there  was  but  a trace  of  sulphur 
found  in  the  run, it  was  thought  that  the  substances  obtained 
from  these  tars  would  not  contain  sulphur, but  on  running  a 
peroxide  fusion  and  determining  the  sulphur, it  v/as  seen  to  be 
present  in  practically  the  same  quantities  as  the  origional 
asphaltenes  contained  it.  Either  all  of  the  sulphur  indicated 
in  the  previous  determination  on  the  whole  run  was  concentrated 
in  these  bodies, or  they  were  the  result  of  polymerization  with 
the  CS^used  as  a solvent.  No  further  work  v/as  done  along  these 
lines, but  an  exhaustive  study  of  these  strange  products  might 
reveal  something  about  the  structure  of  asphaltenes. 

Wax- like  substances  appeared  in  small  quantities , at  various 
times  during  the  investigation.  They  ranged  from  hard, white 
waxes  to  brown , resinlike  bodies, and  invariably  resulted  from 
solutions  of  oils  and  solids  which  had  stood  for  some  time 
exposed  to  the  action  of  light. 

The  coke  resulting  from  the  primary  distillations  ?/as  in 
all  cases  very  dense  and  hard.  Solvents  extracted  nothing  from 
them. 


1 


44.  . 


Ill  Summary. 

The  results  of  the  fore,o;oing  investigation  may  be  s^omm- 
arized  as  follows; 


1 .Hydrocarbons  identified  in  the  straight  xylene  runs. 


Name . 

Formula. 

M.P. (B.p. ) 

How  Identified. 

Xylenes (mixed) 

3.P. 145-150° 

appearance ,B- B* 

Napthalene 

CO 

M.P.  80° 

Pi crate  151° 

Diphenyl  < 

M.P.  70° 

p-brom  deriv  305® 

a- methyl 

napthalene 

00 

B.p. 241-3° 

Appearance  and 
Picrate  112° 

b-methyl 

napthalene 

B.P. 240-2® 

appearance  and 
Picrate  1 1 2® 

b-methyl 

anthracene 

COX'" 

M.P. 202® 

b methyl  anth. 
carbonic  ac.263° 

a-methyl 

anthracene 

O0 

M-P. 202-5° 

a methyl  anth.  ^ 
carbonic  ac.206 

Anthracene 

000 

M.P. 212-14° 

anthraquinone  278° 

Phenanthrene 

exp 

M.P.  98® 

picrate  141-3° 

Ditolyls( mixed) 

B.p. 275-80® 

Isophthalic  295° 

1 ,2  dimethyl 

napthalene 

B.p. 262-4° 

picrate  138° 

Pyrene 

M.P. 145-7° 

picrate  220° 

Chrysene  0X0 

IJ.P.250° 

Appearance, M.P. 

. Hydrocarbons  identified  in 

the  xylene -ethylene  runs. 

Name 

Formula 

M.P. (B.P. ) 

How  Identified. 

Xylenes (mixed) 

B.P. 145-150° 

appearance, B.p. 

Napthalene 

CO 

M.P.  80° 

smell, M.P. ,B. P. 

Diphenyl 

a-raethyl 

napthalene 

M.P.  70° 
B.P. 241-3° 

M.P. ,B.P. 

p-brom  deriv. 

Appearance ,B. P. 

i 

I 

i 


45. 


Name 

Formula 

M.P. (B.P. ) 

How  Identified. 

b-methyl 

napthalene 

CO'"^ 

B.P.  240-242° 

Appearance,B. P. 

a-methyl 

anthracene 

000 

M.P.  202-5° 

a- anthracene 
carbonic  acid  206° 

b-methyl 

anthracene 

COO' 

MP.  202° 

b-anthracene 
carbonic  acid  262° 

Anthracene 

coo 

M.p.  212-4° 

anthraquinone  276-8° 

Phenanthrene 

o9 

M.P  98° 

Pi crate  143° 

1 ,2  dimethyl  05""^ 

napthalene 

B.P. 262-4° 

Pi crate  136° 

2,3  dimethyl 
anthracene 

M.P. 244-6° 

Quinone  l80-2° 

Pyrene 

M.P. 145-7° 

Appearance, M. P. 

Chrysene 

0X0 

M.P. 250° 

Solubility , M.p. 

Hydrocarbons  in  the  napthalene  runs. 

Name 

Formula 

M.P. (B.P. ) 

How  identified. 

b-b-dinapthyl 

\ 

a-a-Dinapthyl 

ocnoo 

M.P. 187-9° 

picrate  183° 

ooxo 

M.p  154° 

Not  found, but 

a-b-dinapthyl 

CXTXO 

M.p. 79-80° 

assumed  to  be  present 

In  summarizing  the  separations  used  the  following  flow  sheets 
gives  the  "best  idea  of  the  methods  in  a condensed  form. 


LIQUIDS 
( steam  J-dlsti nation) 


ORIGIONAL  TAR 

at  1 gt.i  r>n  ^ 


VOLATILE 

(distillation) 

i 

NAPTHALENE 
(filtered  off) 

-i 


NON-VOLATILE 
( inseperable 
heavy  oils, 
none  identif- 
ied. ) 


“I — 

290-360° 

(extracted  with 
hexane ) 


SOLIDS 


AIITHRA(  :ENE 


(least 


o 

360  to  coke, 
(extracted  with 
CSo) 


soluble ) 


Diphenyl, a and  b methyl  napthalenes, 

1,2  dimethyl  napthalene ,ditolyls , 
and  xylene  also  obtained  here  and 
purified  by  special  methods. 


snd  b 

>thyl  anth. 
ire  sol) 

PHSNANTHRENE 
(most  Sol.  ) 


SOLlfebE 

(pyrene, 

dimethyl 

anthracene) 


INSOLUBLE 

(Chrysene) 


IV 


?l!!l 


» 


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ir.  ytt^  • • • >.",  X 


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46. 


The  flow  sheet  showinf^  the  scheme  of  separation  used  in  the 
case  of  the  napthalene  samples  is  given  below. 


ORIGINAL  SAMPLE 
( steamidistillation) 


VOLATILE  WITH  STEAJf 
(Distilled) 


NON-VOLATILE  WITH  STEAiM 
( etherj.  extraction ) 


(found  to  consist  of 
entirely  unchanged 
napthalene ) 


SOLUBLE 

(consists  of  a 
red  oil, not 
identified) 


INSOLUBLE 

SOLIDS 

(benzenej,  extr.  ) 


Soluble 
b-b-dinapthyl . 


Insol. 

(carbon) 


■ '•'’"Ti" '.iM,  vTtJt;'  - f • '’i  < TL^  ' ’’J 


f*^.'’^-  ' tjy  ■, 

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47. 


IV.  Blbllog^raphv. 

1.  Beilstein.  Orp;anische  Cheraie. 

2.  Richter.  Lexicon  der  Kohlenstoff  Verbindungen, 

3.  Millikens  Organic  Analysis, Vol. I. 

4.  Allens  Cominercial  Organic  Analysis. 

5.  Clarkes  Organic  Analysis. 

6.  Qualitative  Organic  Analysis(Chera  21) 

7.  D.T. Jones.  Jour. Soc. Chem. Ind. ,36,P3, I917. 

8.  D.T. Jones.  Jour.of  the  Chem. Soc.  107,0-1582,1915. 

9.  F. Haber.  Ber. ,29,P  2691,1896. 

10.  M.P.E.Berthelot.  Bull. Soc. Chem. Paris. ,7, P 113,122,210,217, 

274. ,1367. 

11.  G-.W. McKee.  Jour  Soc.  Chem.  Ind.  ,23,0  P 403,1904. 

12.  V. N. Ipatieff . Jour. Russ. Phys. Chem. Soc ., 59 ,P  681 , 1 907. 

13.  J. Ostromisslenski  and  J.  Burshanadse. , Jour. Soc. Chem. Ind, 

29, P 682,1910. 

14.  C. Smith  and  W. Lewcock. , Jour. Chem. Soc. , 1 01 ,P  1453,1912. 

15.  W.F.Rittraan,0. Byron, and  G. Egloss. , Ind. and  Eng. Chem, 7, P 1019, 

1915. 

16.  J.E.Zanetti  and  G.Sgloff.,  Jour. Ind. and  Eng. Chem. ,9 ,P350, 191 7. 

17.  C. T.Liebermann  and  O.Berg.  Ber. ,11,p  723,1878. 

18.  K.V. Charelshkov. , Jour. Russ. Phys. Chem. Soc. ,38, 1293-94, I388-92. 

19.  Manson  S. Bradley. , Thesis, 1 920, U.  of  111. 

20.  Edward  E. Charleton. ,Thesis, I9I 8,U. of  111. 

21.  Clark, J.M.  , Jour. Ind. and  Eng. Chem. , Vol  11,#3,Pp  204,1919. 

22.  Cook,0.W.  5ind  Chambers, V.  J.  , Jour.  Am.  Chem.  Soc.  43,2, P 334,1921. 


r f * ^ ff  I.' 


i I • r ; 


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i 


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48. 


23.  Zanetti , J. E. and  Kendall, M.,  Jour. Ind. and  Eng. Chem. Vol. 1 3 , 

#3  Pp. 208-1 t ,Mar. 1921 . 

24.  Rittman,W.F. , Dutton, C. B. and  Dean,E.W.  Bureau  of  Mines, Bull. 

114. 

25.  Cobb,J.W.  and  Dufton, S.F. ,The  Gas  World,Vol.72,Pp485, 1920. 

26.  Bone  and  Coward.  Jour. Chem. Soc. ,93, Ppl 197, 1908. 

27.  Smith  and  Schultz.,  Annalen. , 203 , 1 1 8. 


49. 


Vivita. 

The  writer  of  this  thesis  received  his  early  education  in 
the  grade  and  high  schools  of  Chicago.  He  entered  Loyola 
University  in  the  fall  of  1916  and  continued  there  until 
February , 1 918.  He  then  transferred  to  the  University  of  Illinois, 
where  he  has  been  continuously  up  until  the  present  time. 


